Here's the email I got inviting me to re-post the story. That's all I know : )

  Hi there,

  https://news.ycombinator.com/item?id=10690114 looks good, but didn't
  get much attention. Would you care to repost it? You can do so
  here: https://news.ycombinator.com/repost?id=10690114.

  Please use the same account (krallin), title, and URL. When these match,
  the software will give the repost an upvote from the mods, plus we'll
  help make sure it doesn't get flagged.

  This is part of an experiment in giving good HN submissions multiple
  chances at the front page. If you have any questions, let us know. And
  if you don't want these emails, sorry! Tell us and we won't do it again.

  Thanks for posting good things to Hacker News,
  Daniel

It seems the reposting is only about how interesting the submission is.

I think a resubmitted post gets a small karma bump (1 or 2 points) to help it. But after that it's up to the community to vote.

Software does a first pass through the stories and reviewers look at the rest. "Reviewers" means moderators and a small number of users. Our plan is to open story reviewing to the entire community, but there are some design challenges to solve first. I like the idea of making it a new way of earning karma, because it's both work and community service.

Re criteria for filtering stories: karma isn't a factor; past submissions are. A downside of the latter might be a rich-get-richer effect, but we mitigate that by looking for any earlier submission of the same story and picking that one instead. We don't advise about timing; in fact we randomize the process to reduce timing effects.

We mostly don't send repost invites anymore, but rather re-up the original post by rolling back its internal clock and giving it a random placement near the bottom of the front page. This guarantees a few minutes of community exposure, and regular upvoting decides the rest. On the front page, we display the re-upped timestamp, not the original timestamp, because otherwise it's confusing—only the re-upped time makes sense relative to the other stories on the page. But the original timestamp is available on most of the other pages that list the story, like /submitted and /from, and the discrepancy is temporary, since eventually the two timestamps converge.

The reason we switched from reposts to re-ups is that HN users are averse to duplication. I trust that the programmers among them hold their code to the same standard. We do still send emails when it seems important for the submitter to know that their story may still make the front page—mostly for Show HNs, like this one.

All of this is the latest in a series of experiments we've been running, whose goal is to fix the problem of good stories falling through the cracks on HN. Earlier posts about this, for anyone who wants more background:

https://news.ycombinator.com/item?id=10742610 (more recent, but might as well keep this list up to date)

https://news.ycombinator.com/item?id=10537417

https://news.ycombinator.com/item?id=10395389

https://news.ycombinator.com/item?id=9866140

https://news.ycombinator.com/item?id=8790134

https://news.ycombinator.com/item?id=9828818